ac3 > mp3 in Virtualdub

[davexnet]

Hello - I'm trying to see if there's a good way to convert an avi
while processing the audio from ac3 > mp3.

I know it can be done in Vdub with AC3-ACM, but I don't see a way to
fix the dynamic range or normalize the file.

I've also experimented with Avidemux, looks like it can fix the volume
using it's audio filters, problem is it's much slower than Vdub if I'm also re-encoding the video.

When I re-encode the video, with perhaps a simple resize, I get 250fps in Vdub,
but only about 50-60 in Avidemux. This is on my modest AMD x2 processor.

[guns1inger]

I would use a proper audio editor. Demux the Ac3 file, load it into the latest beta of Audacity using the ffmpeg drivers, normalise, adjust the volume, then save it as an MP3 audio stream, then replace the original in the source.

[davexnet]

Hello Guns1inger, thanks for that alternative. I haven't looked at Audacity or Goldwave for a few years; I've got version 8 of Sound Forge installed but it's so behind the times, it doesn't open FLAC, AC3 or many others.
I used to spin-off the audio with Vdubmod, and use Besweet to convert to 2-channel Wav. The file compression and volume increase was reasonably simple in SF8. and then create the mp3 right there.

On the face of it, it seems like a simple thing, but there's no straightforward solution. Virtualdub with Lame/AC3 ACM is so flexible, as-is Avidemux, yet they have their quirks.

In the 2-hour file I was working with , I re-encoded the video only in Vdub. I then put that as input to Avidemux, with the spun-off ac3 file as audio. Video was set to "copy", while audio was set to convert to mp3 with normalization and dynamic range set. It took 35 minutes, (why so long?), but after the file looked perfect.

I then tried to add soft subs with DivxMux, but it crapped out after a few seconds. Back to square one.